SIEBCHEUS. INSECTS. 281 



deep furrow under the lateral border of the head, and termi- 

 nated in a perfoliated or solid club ; body oval or hemisphe- 

 rical ; mentum large ; maxillary palpi long. 



TIIIBE I. HYDROPHILII. 



Feet for swimming ; first joint of the tarsi short and indistinct ; 

 jaws entirely corneous ; mandibles bidentated or entire at 

 their extremity ; body hemispherical or ovoid, and convex ; 

 thorax always broader than long. 



Gen. SPERCHEUS, Fab. 



Antennas with six joints ; no spines on the legs ; exterior divi- 

 sion of the jaws in the form of palpi, arched, pointed, and 

 downy at its extremity ; body hemispherical. 



S. emarginaius, Lat. Head and thorax blackish ; elytra obscure 

 reddish. 3 lines long. Inhabits Europe, at the roots of aquatic 

 plants. Lat. Gen. pi. 9., fig. 4. 



Gen. HYDROPHILUS, Geoff. 



Antennae with nine joints ; legs terminated by two strong spines, 

 and the hood entire; tarsi with five joints. 



H. piceus, Fab. Olivaceous brown above, and a slight impression on 



each side of the thorax ; elytra with three faint striae formed by 



dotted points. 1J inch long. Inhabits Europe Lat. Gen. ii. 65. 



This genus has been divided by some naturalists into, 1. Those which have the 



anterior tarsi similar in both sexes ; Hydrophilus* Leach ; 2. Those which have no 



carina on the breast ; Hydrobius, Berosus, and LimneHus^ Leach. 



Gen. ELOPHORUS, Fab. Silpha, Lin. 



Palpi terminated by a thicker and oval joint ; club of the an- 

 tennae commencing at the sixth joint ; mandibles simple ; 

 body oblong, depressed. 



E. aquaticus, Fab. Antennae and palpi pale yellow ; head black ; 

 thorax dull gray, more or less bronzed, shagreened and marked 

 with longitudinal grooves ; elytra grayish, with rows of points ; 

 under part of the body black. 3 lines long. Inhabits Europe, 

 in stagnant waters. Lat. Hist. x. pi. 81, fig. 9. 



The E. piceus is the type of the genus Hydrous^ Leach. 



Gen. HYDR^NA, KugeL Elophorus, Fab. 

 Maxillary palpi long, and terminated by a slender pointed joint ; 

 club of the antennae commencing at the third joint ; tarsi fi- 

 liform ; body oval. 



H. riparia, Illig. (E. minimus, Fab.) Very small, black, with two 

 impressed points on the forehead ; thorax entire j elytra with 

 dotted striae, and blackish at their extremity. Found near Paris. 

 Lat. Gen. ii. 70. 



TRIBE II. SPH^RIDIOTA. 

 Feet formed for walking, and the tarsi with five distinct joints, 



